GALESBURG, Ill. — The pesky and destructive emerald ash borer (EAB) has been discovered in two more Illinois counties, state agriculture officials announced last week.

The borer was first discovered in the United States in 2002 in northern Michigan, and for the first time in Illinois in 2006. It is a small, metallic-green beetle native to Asia and its larva burrow into ash trees’ bark and slowly starves them to death over several years.

They only go after ash trees, and in about 10 years, the USDA says the EAB has destroyed more than 25 million ash trees, primarily throughout the Midwest. The beetle was most recently discovered in Lee and Henry counties in northern Illinois.

“In Lee County the beetle was discovered at an industrial site on the east side of Dixon. The detection in Henry County occurred at Baker Park Golf Course in Kewanee,” said Scott Schirmer, the state’s EAB program manager.

The beetle is spread primarily through the transport of firewood, and since the mid-2000s the USDA has placed some states under federal quarantine rules, barring the transport of firewood over state lines.

Within Illinois, there are now 40 counties under quarantine regulations. Firewood cannot be transported across county lines in quarantine areas. Counties adjacent to those already determined to have EAB infestations are automatically quarantined.

Schirmer, though, encouraged everyone in the state to use common sense when it comes to transporting firewood and to keep it local.

“Put the quarantine guidelines into practice by making sure not to transport any firewood or untreated wood products outside their county of origin,” he said. “I’d also encourage tree companies, villages and cities to familiarize themselves with the rules and regulations pertaining to the processing and transporting of ash materials.”

Schirmer said the Baker golf course discovery was due in part to some of the traps the Illinois Department of Agriculture set up throughout the state. He estimated about 15-20 trees on the grounds of the course are infected, and another 5-10 are infected within a quarter-mile of the course.

The Lee County discovery is about 70 miles east of the Quad-Cities in northwestern Illinois, and was made when a lawn care worker for the industrial park reported four ash trees were dying, Schirmer said.

There are certain chemical treatments available that may save the trees if the borer is discovered early enough, he added. The problem, though, is that EAB is difficult to detect early. By the time ash canopy shows symptoms of stress, the borer has been attacking the trunk for 2-3 years.

Anyone who suspects a tree has been infected is urged to contact their county extension office or state forester. More details are available at www.llinois EAB.com